Projector adjustment method, projector, and projector adjustment system

ABSTRACT

A method for adjusting a projector that modulates a plurality of types of color light based on image information to project an image, includes: acquiring first captured image data by using a capturing device to capture a first projected image projected with an optical filter that removes predetermined spectral components not disposed in an optical path inside or outside the projector; acquiring second captured image data by using the capturing device to capture a second projected image projected with the optical filter disposed in the optical path; calculating an adjustment parameter for adjusting the projector based on the first and second captured image data; and adjusting the projector based on the adjustment parameter calculated in the adjustment parameter calculation.

BACKGROUND

1. Technical Field

The present invention relates a projector adjustment method, aprojector, and a projector adjustment system.

2. Related Art

Projectors as projection-type image display apparatus, which in recentyears have had higher image quality and have been produced at lowercost, have been used in a variety of applications. Therefore, the colorreproducibility and image quality of a projector have been moreimportant factors depending on the application in which the projector isused. Since an image projected by a projector suffers from colorunevenness, brightness unevenness, and other individual differences, itis important to precisely improve the image quality of an imageprojected by a projector.

To adjust the image quality of an image projected by a projector, theprojected image is measured by using multiband measurement (multibandimaging), and the measurement result is incorporated in the projector.JP-A-2005-20581, for example, discloses an example of the multibandmeasurement.

JP-A-2005-20581 discloses a technology in which an offset image producedfrom a black signal level successively undergoes multiband measurementfor each of a plurality of primary colors by changing band-pass filterscorresponding to the primary colors to calculate correction data for aprojector. That is, in JP-A-2005-20581, the multiband measurement isperformed by attaching the band-pass filters corresponding to theplurality of primary colors to the camera, which is the imaging-side(measurement-side) apparatus.

The multiband measurement disclosed in JP-A-2005-20581, for example,allows the image quality of an image projected by a projector to befurther improved by measuring the color of the projected image moreaccurately.

In the technology disclosed in JP-A-2005-20581, however, exchanging thefilter attached to the camera is disadvantageously a cumbersome task.Further, exchanging the filter displaces the camera, disadvantageouslyresulting in shift in the captured image and hence reduction inprecision in the measured color of the projected image. To solve theabove problem, it is necessary to use a complicated mechanism forattaching the filter to the camera, resulting in increased cost.

Further, to measure the color of the projected image more accurately, itis necessary to increase the number of bands used in the multibandmeasurement. To this end, for example, the technology disclosed inJP-A-2005-20581 is used. In this case, however, the cost isdisadvantageously further increased.

Moreover, attaching a filter to the camera causes slight refraction dueto the thickness of the filter. It is therefore necessary to incorporatethe measurement result in the projector in consideration of therefraction due to the thickness, which complicates the analysis of themeasurement result.

SUMMARY

An advantage of some aspects of the invention is to provide a projectoradjustment method, a projector, a projector adjustment system, and aprojector adjustment program that allow an image to be adjusted moreaccurately at a low cost by using multiband measurement.

1. An aspect of the invention is a method for adjusting a projector thatmodulates a plurality of types of color light based on image informationto project an image, the method including acquiring first captured imagedata by using a capturing device to capture a first projected imageprojected with an optical filter that removes predetermined spectralcomponents not disposed in an optical path inside or outside theprojector, acquiring second captured image data by using the capturingdevice to capture a second projected image projected with the opticalfilter disposed in the optical path, calculating an adjustment parameterfor adjusting the projector based on the first and second captured imagedata, and adjusting the projector based on the adjustment parametercalculated in the adjustment parameter calculation.

According to the present aspect, the first captured image data areacquired by capturing the first projected image projected with theoptical filter not disposed in the optical path of the projector. Thesecond captured image data are acquired by capturing the secondprojected image projected with the optical filter disposed in theoptical path. The adjustment parameter for adjusting the projector iscalculated based on the first and second captured image data. Therefore,the number of bands can be increased at a low cost in multibandmeasurement. Further, since it is not necessary to provide any opticalfilter on the side of the capturing device, the capturing device willnot be displaced due to an optical filter attaching operation, and themechanism for attaching the capturing device can be simplified.Moreover, no discrepancy in image position will occur between the statein which the optical filter is attached and the state in which theoptical filter is detached, and the adjustment parameter for adjustingthe projector can be calculated without consideration of the refractionresulting from the thickness of the optical filter.

2. In the method for adjusting a projector according to another aspectof the invention, the adjustment parameter is calculated in theadjustment parameter calculation, provided that the first and secondcaptured image data are acquired by using bands the number of which isgreater than the number of bands used in the capturing device.

According to the present aspect, it is not necessary to prepare anexpensive multiband capturing device, but the number of bands can beincreased at a low cost in multiband measurement.

3. In the method for adjusting a projector according to another aspectof the invention, the adjustment parameter calculation includesestimating the spectral distribution associated with the projector basedon the first and second captured image data and the spectral sensitivitycharacteristics of the capturing device, and converting the spectraldistribution estimated in the estimation into color coordinates in apredetermined color space, and the adjustment parameter is calculatedbased on the color coordinates obtained in the conversion.

According to the present aspect, the color of a projected image can bemeasured more accurately at a low cost independently ofprojector-to-projector difference. As a result, the quality of an imageprojected by the projector can be adjusted more precisely.

4. In the method for adjusting a projector according to another aspectof the invention, the adjustment parameter calculation includesestimating the spectral distribution associated with the projector basedon the first and second captured image data, and converting the spectraldistribution estimated in the estimation into color coordinates in apredetermined color space, and the adjustment parameter is calculatedbased on the color coordinates obtained in the conversion.

According to the present aspect, the quality of an image projected bythe projector can be adjusted precisely when the spectral sensitivitycharacteristics of the capturing device are known.

5. In the method for adjusting a projector according to another aspectof the invention, the image information corresponding to the firstprojected image is the same as the image information corresponding tothe second projected image.

According to the present aspect, since the first and second capturedimage data are used to precisely increase the number of bands used inthe multiband measurement, the quality of an image projected by theprojector can be adjusted precisely.

6. In the method for adjusting a projector according to another aspectof the invention, at least one of the luminance and chromaticity of theentire projected image is adjusted in the adjustment of the projectorbased on the adjustment parameter.

According to the present aspect, the quality of an image projected bythe projector can be adjusted precisely.

7. Another aspect of the invention is a projector that modulates aplurality of types of color light based on image information to projectan image, the projector including a projection unit including a lightsource, a light modulation device that modulates the plurality of typesof color light contained in the light flux emitted from the light sourcebased on the image information, and a projection lens that projects thelight modulated by the light modulation device, an optical filterdetachably provided in an optical path inside or outside the projectionunit, the optical filter removing predetermined spectral components, andan capturing device that captures an image projected by the projectionunit. The capturing device acquires first captured image data bycapturing a first projected image projected with the optical filter notdisposed in the optical path inside or outside the projection unit andacquires second captured image data by capturing a second projectedimage projected with the optical filter disposed in the optical path.

According to the present aspect, the first captured image data areacquired by capturing the first projected image projected with theoptical filter not disposed in the optical path of the projector. Thesecond captured image data are acquired by capturing the secondprojected image projected with the optical filter disposed in theoptical path. The adjustment parameter for adjusting the projector iscalculated based on the first and second captured image data. Therefore,the number of bands can be increased at a low cost in multibandmeasurement. Further, since it is not necessary to provide any opticalfilter on the side of capturing device, the capturing device will not bedisplaced due to an optical filter attaching operation, and themechanism for attaching the capturing device can be simplified.Moreover, no discrepancy in image position will occur between the statein which the optical filter is attached and the state in which theoptical filter is detached, and the adjustment parameter for adjustingthe projector can be calculated without consideration of the refractionresulting from the thickness of the optical filter.

8. In the projector according to another aspect of the invention, atleast one of the luminance and chromaticity of the entire projectedimage is adjusted based on the first and second captured image data.

According to the present aspect, a projector capable of preciselyadjusting the quality of a projected image is provided.

9. Another aspect of the invention is a projector adjustment system foradjusting a projector that modulates a plurality of types of color lightbased on image information to project an image, the system including theprojector described above and an image adjustment apparatus that adjustsan image projected by the projector. The image adjustment apparatusincludes a captured image data analyzer that analyzes the first andsecond captured image data, and an adjustment parameter calculator thatcalculates an adjustment parameter for adjusting the projector based onthe analysis result obtained from the captured image data analyzer. Theimage projected by the projector is adjusted based on the adjustmentparameter.

According to the present aspect, the first captured image data areacquired by capturing the first projected image projected with theoptical filter not disposed in the optical path of the projector. Thesecond captured image data are acquired by capturing the secondprojected image projected with the optical filter disposed in theoptical path. The adjustment parameter for adjusting the projector iscalculated based on the first and second captured image data. Therefore,the number of bands can be increased at a low cost in multibandmeasurement. Further, since it is not necessary to provide any opticalfilter on the side of the capturing device, the capturing device willnot be displaced due to an optical filter attaching operation, and themechanism for attaching the capturing device can be simplified.Moreover, no discrepancy in image position will occur between the statein which the optical filter is attached and the state in which theoptical filter is detached, and the adjustment parameter for adjustingthe projector can be calculated without consideration of the refractionresulting from the thickness of the optical filter.

10. In the projector adjustment system according to another aspect ofthe invention, the adjustment parameter calculator calculates theadjustment parameter, provided that the first and second captured imagedata are acquired by using bands the number of which is greater than thenumber of bands used in the capturing device.

According to the present aspect, a projector adjustment system thatrequires no expensive multiband capturing device but can performmultiband measurement with an increased number of bands at a low cost isprovided.

11. In the projector adjustment system according to another aspect ofthe invention, the captured image data analyzer estimates the spectraldistribution associated with the projector based on the first and secondcaptured image data and the spectral sensitivity characteristics of thecapturing device, and converts the estimated spectral distribution intocolor coordinates in a predetermined color space, and the adjustmentparameter calculator calculates the adjustment parameter based on thecolor coordinates converted by the captured image data analyzer.

According to the present aspect, a projector adjustment system capableof precisely adjusting the quality of an image projected by theprojector when the spectral sensitivity characteristics of the capturingdevice are known is provided.

12. In the projector adjustment system according to another aspect ofthe invention, the captured image data analyzer estimates the spectraldistribution associated with the projector based on the first and secondcaptured image data, and converts the estimated spectral distributioninto color coordinates in a predetermined color space, and theadjustment parameter calculator calculates the adjustment parameterbased on the color coordinates converted by the captured image dataanalyzer.

According to the present aspect, a projector adjustment system capableof precisely adjusting the quality of an image projected by theprojector when the spectral sensitivity characteristics of the capturingdevice are known is provided.

13. In the projector adjustment system according to another aspect ofthe invention, the image information corresponding to the imageprojected by using the light that has passed through the optical filteris the same as the image information corresponding to the imageprojected by using the light that has not passed through the opticalfilter.

According to the present aspect, since the captured image data obtainedwhen the optical filter is detached and the captured image data obtainedwhen the optical filter is attached are used to precisely increase thenumber of bands used in the multiband measurement, the quality of animage projected by the projector can be adjusted precisely.

14. In the projector adjustment system according to another aspect ofthe invention, the projector adjusts at least one of the luminance andchromaticity of the entire projected image based on the adjustmentparameter.

According to the present aspect, the quality of an image projected bythe projector can be adjusted precisely.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanyingdrawings, wherein like numbers refer to like elements.

FIG. 1 shows an exemplary configuration of a projector adjustment systemin a first embodiment according to the invention.

FIGS. 2A and 2B describe the number of bands used in a capturing devicein the first embodiment.

FIG. 3 is a block diagram showing an exemplary configuration of theprojector adjustment system shown in FIG. 1.

FIG. 4 is a block diagram showing an exemplary configuration of acaptured image data analyzer shown in FIG. 3.

FIG. 5 describes the operation of a color space converter.

FIG. 6 describes the operation of an adjustment parameter calculator.

FIG. 7 describes a specific process carried out in the adjustmentparameter calculator.

FIG. 8 is a block diagram showing an exemplary configuration of aluminance/chromaticity adjuster shown in FIG. 3.

FIG. 9 shows an exemplary configuration of a projection unit shown inFIG. 3.

FIG. 10 describes the operation of the projector adjustment system inthe first embodiment.

FIG. 11 is a block diagram showing an exemplary hardware configurationof an image adjustment apparatus in the first embodiment.

FIG. 12 shows a flowchart of exemplary processes carried out by theimage adjustment apparatus in the first embodiment.

FIG. 13 shows an exemplary configuration of a projection unit in a thirdembodiment according to the invention.

FIG. 14 shows an exemplary configuration of a projection unit in afourth embodiment according to the invention.

FIG. 15 shows an exemplary configuration of a projection unit in a fifthembodiment according to the invention.

FIG. 16 shows an exemplary configuration of a projection unit in a sixthembodiment according to the invention.

FIG. 17 is an exemplary perspective view showing an exterior key portionof a projector in a seventh embodiment according to the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the invention will be described below in detail withreference to the drawings. The embodiments described below are notintended to unreasonably limit the scope of the invention set forth inthe claims. Further, the configurations described below are notnecessarily essential to achieve the advantage of the invention.

First Embodiment

FIG. 1 shows an exemplary configuration of a projector adjustment systemin a first embodiment according to the invention.

A projector adjustment system 10 in the first embodiment includes aprojector PJ as an image display apparatus (image projection apparatus)and an image adjustment apparatus 200. The projector PJ includes acapturing device (camera) 300 and projects an image on a screen SCR as aprojection surface. While the first embodiment will be described byassuming that the projector PJ houses the capturing device 300, thecapturing device 300 may be provided external to the projector PJ.

The capturing device 300 can perform multiband measurement by acquiringcaptured image data on an image projected on the screen SCR by theprojector PJ in RGB multiple bands (three bands). The captured imagedata acquired by the capturing device 300 are outputted to the imageadjustment apparatus 200.

The image adjustment apparatus 200 is connected to the projector PJ andthe capturing device 300 and capable of controlling the projector PJ andthe capturing device 300. More specifically, the image adjustmentapparatus 200 adjusts the image quality of an image projected by theprojector PJ based on the captured image data (measurement results) fromthe capturing device 300, which captures the image projected by theprojector PJ. The image adjustment apparatus 200 can send to theprojector PJ adjustment parameters calculated based on the capturedimage data from the capturing device 300. The projector PJ can adjustthe luminance and chromaticity of the entire screen based on adjustmentparameters. The function of the image adjustment apparatus 200 describedabove is achieved, for example, by software processing using a personalcomputer or any other suitable component or hardware processing usingdedicated hardware or any other suitable component.

In the first embodiment, to precisely improve the image quality of animage projected by the projector PJ, the number of bands used in themultiband measurement performed by the capturing device 300 is virtuallyincreased, whereby the color of the projected image is more accuratelymeasured at a low cost. To this end, an optical filter that removespredetermined spectral components is detachably provided in the opticalpath of the projector PJ, whereby 6-band multiband measurement isvirtually achieved by attaching or detaching the optical filter. It isassumed that the removal function of the optical filter is achieved byreflection or absorption of unwanted light having predetermined spectralcomponents.

FIGS. 2A and 2B describe the number of bands used in the capturingdevice 300 in the first embodiment. FIG. 2A shows an example of thespectral sensitivity characteristics of the bands used in the capturingdevice 300. FIG. 2B shows an example of the spectral sensitivitycharacteristics obtained when an image projected by the projector PJ iscaptured by the capturing device 300 with the optical filter disposed inthe optical path as well as the spectral sensitivity characteristicsshown in FIG. 2A.

In FIGS. 2A and 2B, the horizontal axis represents the wavelength oflight, and the vertical axis represents the spectral sensitivity. TheRGB three bands used in the capturing device 300 have the spectralsensitivity characteristics shown in FIG. 2A. The capturing device 300having the spectral sensitivity characteristics shown in FIG. 2A iscommercially available at a relatively low cost. Disposing and notdisposing an optical filter in the optical path of the projector PJproduces a state in which the optical filter is disposed in the opticalpath (the optical filter is attached) and a state in which the opticalfilter is not disposed in the optical path (the optical filter isdetached), and the spectral sensitivity characteristics in the twostates are defined for each of the bands used in the capturing device300, whereby the 3-band capturing device 300 can virtually perform6-band multiband measurement.

The optical filter described above can be a filter that removes(reflects or absorbs) the light having wavelength bands from ultravioletto 440 nm and from 550 to 630 nm, as shown in FIG. 2B. In FIG. 2B, forexample, when the optical filter is disposed in the optical path, thespectral sensitivity characteristics are nearly “0” for the light havingwavelength bands from ultraviolet to 440 nm and from 550 to 630 nm ineach of the bands used in the capturing device 300. As described above,disposing and not disposing the optical filter in the optical path ofthe projector PJ allows not only the spectral sensitivitycharacteristics in the bands used in the capturing device 300 shown inFIG. 2A to be obtained but also the spectral sensitivity characteristicsin the bands in the state in which the optical filter is disposed in theoptical path to be obtained, for example, as shown in FIG. 2B.

According to the first embodiment, it is therefore not necessary toprepare an expensive multiband capturing device, but the number of bandscan be increased at a low cost in multiband measurement. Further, sinceit is not necessary to provide any optical filter on the capturingdevice side, the capturing device will not be displaced due to anoptical filter attaching operation, and the mechanism for attaching thecapturing device can be simplified.

FIG. 3 is a block diagram showing an exemplary configuration of theprojector adjustment system 10 shown in FIG. 1. In FIG. 3, the portionsthat are the same as those in FIG. 1 have the same reference characters,and no description of these portions will be made as appropriate.

The image adjustment apparatus 200 includes an image informationproducer 210, a captured image data analyzer 220, and an adjustmentparameter calculator 230.

The image information producer 210 produces image informationcorresponding to content images and outputs the image information to theprojector PJ. The function of the image information producer 210 mayalternatively be provided external to the image adjustment apparatus200.

The captured image data analyzer 220 analyzes captured image data on aprojected image acquired by the capturing device 300 to calculate thespectral distribution associated with the projector PJ and converts thespectral distribution into color coordinates in a predetermined colorspace to produce conversion information. The adjustment parametercalculator 230 then calculates adjustment parameters for adjusting theprojector PJ based on the conversion information.

FIG. 4 is a block diagram showing an exemplary configuration of thecaptured image data analyzer 220 shown in FIG. 3. In FIG. 4, theportions that are the same as those in FIG. 3 have the same referencecharacters, and no description of these portions will be made asappropriate.

The captured image data analyzer 220 includes a spectral distributionestimator 222 and a color space converter 224.

The spectral distribution estimator 222 uses the captured image datafrom the capturing device 300 to estimate the spectral distributionassociated with the projector PJ. To allow the spectral distributionestimator 222 to determine the spectral distribution associated with theprojector PJ, it is necessary to prepare information on the spectraldistribution of external illumination, the spectral reflectance of thescreen SCR, and the spectral sensitivity characteristics of thecapturing device 300. In the first embodiment, it is assumed that thescreen SCR shows uniform reflection characteristics in a dark room, andthe spectral distribution estimator 222 estimates the spectraldistribution associated with the projector PJ based on the capturedimage data from the capturing device 300 and the spectral sensitivitycharacteristics of the capturing device 300 that have been measured inadvance.

To estimate the spectral distribution associated with the projector PJ,for example, the estimation method described in the following ReferenceLiterature 1 can be used: “Introduction to spectral image processing”edited by Yoichi Miyake, Chapter 4, Spectral Reflectance EstimationTheory, University of Tokyo Press, pp. 63-84. Reference Literature 1describes that the spectral distribution obtained when the light from aprojector is reflected off a screen can be estimated from captured imagedata obtained in multiband measurement using a small number of bandsbased on an estimation method using a minimum norm solution and aprimary component, a minimum mean squared error law, or any othersuitable method.

In the first embodiment, it is assumed that the captured image data fromthe capturing device 300, the number of bands of which is “3”, are6-band captured image data obtained by attaching and detaching anoptical filter. In this case, the captured image data g is expressed bya 6×1 matrix. When the number of wavelength sampling operations is L,the spectral sensitivity characteristics of the capturing device 300that have been measured in advance are expressed by an L×6 matrix. Now,let E be the spectral distribution (L×L matrix) associated with theprojector PJ, r be the spectral reflectance (L×1 matrix) of the screenSCR, and n be noise (6×1 matrix). The captured image data g is expressedby the following equation:

g=S ^(t) ·E·r+n  (1)

In the above equation, S is a matrix representing the spectraldistribution (L×6 matrix) associated with the capturing device 300. Inthe matrix S (=[s₁, s₂, . . . , s₆]), the i-th column s_(i) representsthe spectral sensitivity characteristics in the i-th band. S_(t) is thetransposed matrix of the matrix S.

Now, a solution whose norm is the least in the solution space isselected, and it is assumed that a noise-free condition is satisfied(i.e., n=0). In this case, the captured image data g is expressed asfollows:

g=S ^(t) ·E·r  (2)

Since it is assumed that the screen SCR shows uniform reflectioncharacteristics, the spectral reflectance of the screen SCR r is amatrix whose each element is “1”. Therefore, the following equation isobtained:

g=S ^(t) ·E  (3)

As described in Reference Literature 1, for example, the followingequation is derived from the equation (3):

E=S·(S ^(t) ·S)⁻¹ ·g  (4)

Therefore, when the spectral sensitivity characteristics of thecapturing device 300 is known and captured image data can be acquiredfrom the capturing device 300, the spectral distribution associated withthe projector PJ can be estimated.

The color space converter 224 shown in FIG. 4 converts the spectraldistribution associated with the projector PJ that has been estimated bythe spectral distribution estimator 222 into color coordinates in apredetermined color space and outputs the conversion result to theadjustment parameter calculator 230.

FIG. 5 describes the operation of the color space converter 224. In FIG.5, the horizontal axis represents the wavelength of light, and thevertical axis represents the spectral response. FIG. 5 shows an exampleof a color matching function representing the spectral responsecorresponding to human eyes.

The color space converter 224 outputs values in a CIE (CommissionInternationale de l'Eclairage) colorimetric system corresponding to thespectral distribution associated with the projector PJ that has beenestimated by the spectral distribution estimator 222. More specifically,the color space converter 224 outputs values in the XYZ colorimetricsystem (CIE 1931 colorimetric system) corresponding to the spectraldistribution associated with the projector PJ to the adjustmentparameter calculator 230. The color space converter 224 thereforeweights the spectral distribution associated with the projector PJ thathas been estimated by the spectral distribution estimator 222 inaccordance with the color matching function shown in FIG. 5, sums theweighted spectral distributions, and outputs values in the XYZcolorimetric system as conversion information.

Values in a CIE colorimetric system described above are not limited tovalues in the XYZ colorimetric system but may be values in the X₁₀Y₁₀Z₁₀colorimetric system (CIE 1964 colorimetric system), chromaticitycoordinates (x, y) in the XYZ colorimetric system, chromaticitycoordinates (x₁₀, y₁₀) in the X₁₀Y₁₀Z₁₀ colorimetric system, thelightness and color coordinates in the CIELAB color space (CIE 1976L*a*b* color space), or the lightness and color coordinates in theCIELUV color space (CIE 1976 L*u*v* color space).

As described above, the captured image data analyzer 220 can analyzecaptured image data acquired by the capturing device 300 to producevalues in the XYZ colorimetric system capable of quantitativerepresentation independent of the difference in the spectralcharacteristics of the projector PJ.

FIG. 6 describes the operation of the adjustment parameter calculator230. FIG. 6 shows an example of how a value X_(R) in the XYZcolorimetric system for an input value of the R component of imageinformation changes before and after the projector PJ is adjusted byusing an adjustment parameter. The behavior shown in FIG. 6 also appliesto how a value Y_(G) in the XYZ colorimetric system for an input valueof the G component of the image information changes before and after theprojector PJ is adjusted and how a value X_(B) in the XYZ colorimetricsystem for an input value of the G component of the image informationchanges.

FIG. 7 describes a specific process carried out in the adjustmentparameter calculator 230.

The adjustment parameter calculator 230 in the first embodimentcalculates an input value Rin′ of the R component from the projector PJin such a way that the measured value for an input value Rin of the Rcomponent of the image information coincides with a predeterminedreference value Xout. The adjustment parameter calculator 230 thendetermines an adjustment parameter for correction in such a way that theinput value Rin′ is outputted when the input value of the R component ofthe image information is Rin, and outputs the adjustment parameter tothe projector PJ.

The adjustment parameters are determined by modifying the conversionequation, for example, shown in FIG. 7 as the lightness and colorcoordinates (L, U, V) in the CIELUV color space of an image projected bythe projector PJ, the lightness and color coordinates corresponding tothe input value Rin of the R component, the input value Gin of the Gcomponent, and the input value Bin of the B component. Therefore, theadjustment parameters for providing the lightness and color coordinatesmay be outputted to the projector PJ.

As described above, after the estimated spectral distribution associatedwith the projector PJ is converted into color coordinates in apredetermined color space, the adjustment parameter calculator 230calculates adjustment parameters to be used to adjust the lightness andchromaticity of the entire projected image.

The thus calculated adjustment parameters are outputted to the projectorPJ. The configuration of the projector PJ will now be described below.

As shown in FIG. 3, the projector PJ includes a projection unit 100 asan image display unit, a luminance/chromaticity adjuster 180 as an imageprocessor, and an image information input unit 190.

The projection unit 100 includes an optical filter FL that can bedisposed in the optical path provided in the projection unit 100, andcan project an image while switching the projection state between astate in which the optical filter is disposed in the optical path (astate in which the optical filter FL is attached) and a state in whichthe optical filter is not disposed in the optical path (a state in whichthe optical filter FL is detached). The projection unit 100 projects animage that does not contain the light removed by the optical filter FLwhen the optical filter FL is attached, whereas projecting an image thatalso contains the light to be removed by the optical filter FL when theoptical filter FL is detached.

The image information input unit 190 carries out a reception interfaceprocess of receiving image information from the image adjustmentapparatus 200 and outputs the image information on an input image to theluminance/chromaticity adjuster 180. The reception interface process caninclude a physical layer signal level conversion process and aprogressive conversion process.

The luminance/chromaticity adjuster 180 corrects at least one of theluminance and the chromaticity corresponding to the image informationfrom the image information input unit 190 based on the adjustmentparameters from the image adjustment apparatus 200, and outputs thecorrected image information to the projection unit 100.

The projection unit 100 changes the rate at which the light from a lightsource (not shown) is modulated based on the image information havingbeen adjusted (corrected) by the luminance/chromaticity adjuster 180,and projects the modulated light on the screen SCR. More specifically,the projection unit 100 projects an image by modulating multiple typesof color light emitted from the light source based on the imageinformation from the luminance/chromaticity adjuster 180.

FIG. 8 is a block diagram showing an exemplary configuration of theluminance/chromaticity adjuster 180 shown in FIG. 3. In FIG. 8, theportions that are the same as those in FIG. 3 have the same referencecharacters, and no description of these portions will be made asappropriate.

The luminance/chromaticity adjuster 180 includes an adjustment parameterstorage section 182 and a signal converter 184. Theluminance/chromaticity adjuster 180 receives the adjustment parameterscalculated by the adjustment parameter calculator 230 in the imageadjustment apparatus 200, and the adjustment parameter storage section182 stores the inputted adjustment parameters. The signal converter 184corrects the image information from the image information input unit 190based on the adjustment parameters stored in the adjustment parameterstorage section 182 and outputs the corrected image information to theprojection unit 100.

For example, the adjustment parameter storage section 182 storesadjustment parameters for all grayscales that the image information canexpress, and the signal converter 184 can correct the pre-correctionimage information based on the adjustment parameters corresponding tothe grayscales specified by the image information. Alternatively, forexample, the adjustment parameter storage section 182 stores adjustmentparameters for discrete ones of all grayscales that the imageinformation can express, and the signal converter 184 can correct thepre-correction image information based on the adjustment parameterscorresponding to the grayscales specified by the image information orthe adjustment parameters obtained by interpolating the adjustmentparameters stored in the adjustment parameter storage section 182.

FIG. 9 shows an exemplary configuration of the projection unit 100 shownin FIG. 3. The projection unit 100 of the projector PJ shown in FIG. 9has what is called a three-panel configuration, but the projection unitaccording to an aspect of the invention does not necessarily have whatis called a three-panel configuration.

The projection unit 100 includes a light source 110, integrator lenses112 and 114, a polarization conversion element 116, a superimposing lens118, a dichroic mirror for the R component 120R, a dichroic mirror forthe G component 120G, a reflection mirror 122, a field lens for the Rcomponent 124R, a field lens for the G component 124G, a liquid crystalpanel for the R component 130R (first light modulation device), a liquidcrystal panel for the G component 130G (second light modulation device),a liquid crystal panel for the B component 130B (third light modulationdevice), a relay system 140, across dichroic prism 160, the opticalfilter FL, and a projection lens 170. The liquid crystal panels used asthe liquid crystal panel for the R component 130R, the liquid crystalpanel for the G component 130G, and the liquid crystal panel for the Bcomponent 130B are transmissive liquid crystal display devices. Therelay system 140 includes relay lenses 142, 144, and 146 and reflectionmirrors 148 and 150.

The light source 110 is formed of an ultra-high pressure mercury lamp orany other suitable lamp and emits light containing at least R componentlight, G component light, and B component light. The integrator lens 112includes a plurality of lenslets for dividing the light from the lightsource 110 into a plurality of segmented light fluxes. The integratorlens 114 includes a plurality of lenslets corresponding to the pluralityof lenslets in the integrator lens 112. The superimposing lens 118superimposes the segmented light fluxes having exited through theplurality of lenslets in the integrator lens 114 on the liquid crystalpanels.

The polarization conversion element 116 includes a polarizing beamsplitter array and a λ/2 plate and converts the light from the lightsource 110 into substantially one type of polarized light. Thepolarizing beam splitter array has a structure in which a polarizationseparating layer and a reflection layer are alternately arranged, eachof the polarization separating layers separating the segmented lightfluxes divided by the integrator lens 112 into p-polarized light ands-polarized light, each of the reflection layers changing the directionof the light from the corresponding polarization separating layer. Thetwo types of polarized light separated by the polarization separatinglayers pass through the λ/2 plate, where the polarization directions ofthe polarized light are aligned. The substantially one type of polarizedlight converted by the polarization conversion element 116 is incidenton the superimposing lens 118.

The light having passed through the superimposing lens 118 is incidenton the dichroic mirror for the R component 120R. The dichroic mirror forthe R component 120R has a function of reflecting the R component lightwhereas transmitting the G component light and the B component light.The light having passed through the dichroic mirror for the R component120R is incident on the dichroic mirror for the G component 120G,whereas the light reflected off the dichroic mirror for the R component120R is reflected off the reflection mirror 122 and guided to the fieldlens for the R component 124R.

The dichroic mirror for the G component 120G has a function ofreflecting the G component light whereas transmitting the B componentlight. The light having passed through the dichroic mirror for the Gcomponent 120G is incident on the relay system 140, whereas the lightreflected off the dichroic mirror for the G component 120G is guided tothe field lens for the G component 124G.

To reduce the difference in the optical path length as much as possiblebetween the B component light passing through the dichroic mirror forthe G component 120G and the other R and G component light, the relaylenses 142, 144, and 146 in the relay system 140 are used to correct thedifference in the optical path length. The light having passed throughthe relay lens 142 is reflected off the reflection mirror 148 and guidedto the relay lens 144. The light having passed through the relay lens144 is reflected off the reflection mirror 150 and guided to the relaylens 146. The light having passed through the relay lens 146 is incidenton the liquid crystal panel for the B component 130B.

The light incident on the field lens for the R component 124R isconverted into parallelized light and incident on the liquid crystalpanel for the R component 130R. The liquid crystal panel for the Rcomponent 130R functions as a light modulation device (light modulator),and the transmittance (transmission rate, modulation rate) thereof ischanged based on image information on the R component. Therefore, thelight incident on the liquid crystal panel for the R component 130R(first color component light) is modulated based on the imageinformation on the R component having been corrected by theluminance/chromaticity adjuster 180, and the modulated light is incidenton the cross dichroic prism 160.

The light incident on the field lens for the G component 124G isconverted into parallelized light and incident on the liquid crystalpanel for the G component 130G. The liquid crystal panel for the Gcomponent 130G functions as a light modulation device (light modulator),and the transmittance (transmission rate, modulation rate) thereof ischanged based on image information on the G component. Therefore, thelight incident on the liquid crystal panel for the G component 130G(second color component light) is modulated based on the imageinformation on the G component having been corrected by theluminance/chromaticity adjuster 180, and the modulated light is incidenton the cross dichroic prism 160.

The liquid crystal panel for the B component 130B, on which the lighthaving passed through the relay lenses 142, 144, and 146 and having beenconverted into parallelized light is incident, functions as a lightmodulation device (light modulator), and the transmittance (transmissionrate, modulation rate) thereof is changed based on image information onthe B component. Therefore, the light incident on the liquid crystalpanel for the B component 130B (third color component light) ismodulated based on the image information on the B component having beencorrected by the luminance/chromaticity adjuster 180, and the modulatedlight is incident on the cross dichroic prism 160.

The liquid crystal panel for the R component 130R, the liquid crystalpanel for the G component 130G, and the liquid crystal panel for the Bcomponent 130B have the same configuration. Each of the liquid crystalpanels encapsulates and seals liquid crystal molecules, an electro-opticmaterial, between a pair of transparent glass substrates. For example, apolysilicon thin-film transistor is used as a switching device tomodulate the transmission rate of the corresponding color light inaccordance with image information associated with each pixel.

The cross dichroic prism 160 has a function of combining the lightfluxes incident from the liquid crystal panel for the R component 130R,the liquid crystal panel for the G component 130G, and the liquidcrystal panel for the B component 130B and outputting the combined lightas exiting light.

The optical filter FL is detachably provided in the optical path of thecombined light (exiting light) from the cross dichroic prism 160 betweenthe cross dichroic prism 160 and the projection lens 170. That is, theoptical filter FL can be disposed in the optical path of the combinedlight from the cross dichroic prism 160, whereas disposed in a positionoutside the optical path of the combined light from the cross dichroicprism 160. The optical filter FL is, for example, a filter that removes(reflects or absorbs) the light having wavelength bands from ultravioletto 440 nm and from 550 to 630 nm.

When the optical filter FL is disposed in the optical path of thecombined light from the cross dichroic prism 160 (when the opticalfilter FL is attached), the combined light from the cross dichroic prism160 is incident on the optical filter FL. The optical filter FL reflectsthe light having predetermined spectral components whereas transmittingthe light having the remaining spectral components as described above.The light having passed through the optical filter FL is incident on theprojection lens 170.

On the other hand, when the optical filter FL is disposed in a positionoutside the optical path of the combined light from the cross dichroicprism 160 (when the optical filter FL is detached), the combined lightfrom the cross dichroic prism 160 does not pass through the opticalfilter FL but is directly incident on the projection lens 170.

The projection lens 170 focuses the combined light directly from thecross dichroic prism 160 or the combined light having passed through theoptical filter FL into an enlarged output image on the screen SCR. Theprojection lens 170 has a function of enlarging or shrinking the imagein accordance with a zoom magnification factor.

In the thus configured projection unit 100, a moving mechanism (notshown) moves the optical filter FL into the optical path of the lightflux described above or to a position outside the optical path. Forexample, the optical filter FL is disposed in the optical axis of theprojection lens 170 in such a way that the optical filter FL issubstantially perpendicular to the optical axis, and the movingmechanism (not shown) can translate the optical filter FL out of theoptical path. Conversely, the moving mechanism can translate the opticalfilter FL located in a position outside the optical path into theoptical path in such a way that the optical filter FL is substantiallyperpendicular to the optical axis of the projection lens 170.

The moving mechanism for moving the optical filter FL described abovemay be a mechanism manually operated or a mechanism controlled bycontrol information from the image adjustment apparatus 200 or theprojector PJ.

The thus configured projector adjustment system 10 adjusts the qualityof an image formed by the projector PJ in the following manner:

FIG. 10 describes the operation of the projector adjustment system 10 inthe first embodiment. In FIG. 10, the portions that are the same asthose in FIG. 3 have the same reference characters, and no descriptionof these portions will be made as appropriate.

In the projector adjustment system 10, the image adjustment apparatus200 first outputs image information corresponding to a predeterminedtest image to the projector PJ (T1), and the projector PJ projects thetest image with the optical filter FL described above detached (firstprojected image). The test image can be, for example, an image withpixels of the same grayscale arranged thereacross. The capturing device300 then captures the image projected by the projector PJ on the screenSCR (first projected image) and sends the captured image data (firstcaptured image data) to the image adjustment apparatus 200 (T2).

In the state in which the optical filter FL is detached as describedabove, the test image is repeatedly projected and captured, for example,for multiple types of grayscale. In this way, captured image data on theprojected image using the light that have not passed through the opticalfilter FL can be acquired.

Subsequently, the image adjustment apparatus 200 outputs imageinformation corresponding to a predetermined test image to the projectorPJ (T3), and the projector PJ projects the test image with the opticalfilter FL described above attached (second projected image). The testimage is the same as the test image used when the optical filter FL isdetached. That is, the image information corresponding to the projectedimage using the light that has passed through the optical filter FL isthe same as the image information corresponding to the projected imageusing the light that has not passed through the optical filter FL. Thecapturing device 300 then captures the image projected by the projectorPJ on the screen SCR (second projected image) and sends the capturedimage data (second captured image data) to the image adjustmentapparatus 200 (T4).

In the state in which the optical filter FL is attached as describedabove, the test image is repeatedly projected and captured, for example,for multiple types of grayscale.

The image adjustment apparatus 200 then uses a pair of captured imagedata obtained when the optical filter FL is attached and captured imagedata obtained when the optical filter FL is detached, for example, foreach of the grayscales to calculate adjustment parameters for correctingcolor unevenness, brightness unevenness, and other individualdifferences in the projector PJ. The image adjustment apparatus 200sends an adjustment command containing the adjustment parameters to theprojector PJ (T5). The projector PJ, which has received the adjustmentcommand, adjusts the luminance and chromaticity of the entire screenbased on the adjustment parameters specified by the adjustment command.

The function of adjusting and controlling the image quality of an imageprojected by the projector PJ performed by the image adjustmentapparatus 200 may be implemented by hardware or software processing.

FIG. 11 is a block diagram showing an exemplary hardware configurationof the image adjustment apparatus 200 in the first embodiment.

The image adjustment apparatus 200 includes a CPU 250, an I/F circuit260, a read only memory (ROM) 270, a random access memory (RAM) 280, anda bus 290, and the CPU 250, the I/F circuit 260, the ROM 270, and theRAM 280 are electrically connected to one another via the bus 290.

For example, the ROM 270 stores a program that achieves the function ofthe image adjustment apparatus 200. The CPU 250 reads the program storedin the ROM 270 and performs software processing corresponding to theprogram to achieve the function of the image adjustment apparatus 200.The RAM 280 is used as a work area where the CPU 250 carries outprocesses or used as a buffer area for the I/F circuit 260 and the ROM270. The I/F circuit 260 carries out an output interface process ofoutputting image information and adjustment parameters to the projectorPJ and an input interface process of inputting captured image data fromthe capturing device 300 in the projector PJ.

FIG. 12 is a flowchart of exemplary processes carried out by the imageadjustment apparatus 200 in the first embodiment. For example, the ROM270 shown in FIG. 11 stores a program that specifies the processprocedure shown in FIG. 12, and the CPU 250 carries out the processescorresponding to the program read from the ROM 270. The functions of theportions that form the image adjustment apparatus 200 can be performedby carrying out the software processes shown in FIG. 12.

First, the image adjustment apparatus 200 carries out a process ofdetaching the optical filter (step S10). That is, the image adjustmentapparatus 200 outputs a command to the projector PJ including theprojection unit 100 configured as shown in FIG. 9, and the commandcontrols the projector PJ to dispose the optical filter FL in a positionoutside the optical path. Alternatively, the image adjustment apparatus200 outputs a command to the projector PJ to instruct an operatorthrough an operation panel, an indicator lamp, or any other suitablecomponent (not shown) of the projector PJ to dispose the optical filterin a position outside the optical path.

The image adjustment apparatus 200 then produces image informationcorresponding to a test image in the image information producer 210,sends the image information to the projector PJ, and instructs theprojector PJ to project the test image (first projected image) as afirst projection step (step S12). In the step S12, the projector PJ,which has received the command from the image adjustment apparatus 200,may project the image, or the operator may be instructed through theoperation panel, the indicator lamp, or any other suitable component(not shown) of the projector PJ to project the image.

Subsequently, the image adjustment apparatus 200 sends a command to theprojector PJ as a first image capturing step to instruct the capturingdevice 300 to capture the test image (acquire first captured image data)displayed in the step S12 (step S14).

More specifically, the image adjustment apparatus 200 first outputs tothe projector PJ image information on the test image whose grayscalesfor the G and B components except the R component are “0”, and thecapturing device 300 captures the test image corresponding to the imageinformation displayed by the projector PJ on the screen SCR. The imageadjustment apparatus 200 then outputs to the projector PJ imageinformation on the test image whose grayscales for the G and Bcomponents except the R component are “1”, and the capturing device 300captures the projected image as described above. The test image isrepeatedly displayed and captured until the G and B component grayscalesexcept the R component grayscale reach a maximum value. Similarly, thesame procedure described above is repeated for each of the test imagescorresponding to the R and B component grayscales, except the Gcomponent grayscale, from “0” to the maximum value, and then the sameprocedure is repeated for each of the test images corresponding to the Rand G component grayscales, except the B component grayscale, from “0”to the maximum value.

The operations of projecting a test image and capturing the projectedimage described above are repeated for all the test images (step S16:N). It is desirable that each of the test images is an image with pixelsof the same grayscale arranged thereacross and multiple types of testimage are prepared for each of the grayscales, as described above.

When the image capturing operation is completed for all the test imageswith the optical filter FL detached (step S16: Y), the image adjustmentapparatus 200 carries out a process of attaching the optical filter(step S18).

In the step S18, the image adjustment apparatus 200 outputs a command tothe projector PJ including the projection unit 100 configured as shownin FIG. 9, and the command controls the projector PJ to dispose theoptical filter FL in the optical path. Alternatively, the imageadjustment apparatus 200 outputs a command to the projector PJ toinstruct the operator through the operation panel, the indicator lamp,or any other suitable component (not shown) of the projector PJ todispose the optical filter in the optical path.

The image adjustment apparatus 200 then produces image informationcorresponding to a test image in the image information producer 210,sends the image information to the projector PJ, and instructs theprojector PJ to project the test image (second projected image) as asecond projection step (step S20). In the step S20, the projector PJ,which has received the command from the image adjustment apparatus 200,may project the image, or the operator may be instructed through theoperation panel, the indicator lamp, or any other suitable component(not shown) of the projector PJ to project the image.

Subsequently, the image adjustment apparatus 200 sends a command to theprojector PJ as a second image capturing step to instruct the capturingdevice 300 to capture the test image (acquire second captured imagedata) displayed in the step S20 (step S22).

More specifically, the image adjustment apparatus 200 first outputs tothe projector PJ image information on the test image whose grayscalesfor the G and B components except the R component are “0”, and thecapturing device 300 captures the test image corresponding to the imageinformation displayed by the projector PJ on the screen SCR. The imageadjustment apparatus 200 then outputs to the projector PJ imageinformation on the test image whose grayscales for the G and Bcomponents except the R component are “1”, and the capturing device 300captures the projected image as described above. The test image isrepeatedly displayed and captured until the G and B component grayscalesexcept the R component grayscale reach a maximum value. Similarly, thesame procedure described above is repeated for each of the test imagescorresponding to the R and B component grayscales, except the Gcomponent grayscale, from “0” to the maximum value, and then the sameprocedure is repeated for each of the test images corresponding to the Rand G component grayscales, except the B component grayscale, from “0”to the maximum value.

The operations of projecting a test image and capturing the projectedimage described above are repeated for all the test images (step S24:N). It is desirable that each of the test images is an image with pixelsof the same grayscale arranged thereacross and multiple types of testimage are prepared for each of the grayscales, as described above.

When the image capturing operation is completed for all the test imageswith the optical filter FL attached (step S24: Y), the image adjustmentapparatus 200 calculates adjustment parameters, as described above, asan adjustment parameter calculation step (step S26). That is, the imageadjustment apparatus 200 estimates the spectral distribution associatedwith the projector PJ in the captured image data analyzer 220 based onthe captured image data obtained in the steps S14 and S22 and thespectral sensitivity characteristics of the capturing device 300,converts the estimated spectral distribution into color coordinates in apredetermined color space, and then calculates adjustment parameters inthe adjustment parameter calculator 230 based on the converted values.That is, the step S26 includes an estimation step of estimating thespectral characteristics of the projector PJ based on the first capturedimage data acquired in the step S14, the second captured image dataacquired in the step S22, and the spectral sensitivity characteristicsof the capturing device 300, and a conversion step of converting thespectral distribution estimated in the estimation step into colorcoordinates in a predetermined color space, and adjustment parametersare calculated based on the color coordinates obtained in the conversionstep. In this way, in the step S26, the captured image data obtained inthe step S14 and the captured image data obtained in the step S22, whichare captured image data acquired by using a greater number of bands thanthe number of bands used in the capturing device 300, can be used tocalculate the adjustment parameters.

The adjustment parameter calculator 230 determines adjustment parametersas the lightness and color coordinates (L, U, V) in the CIELUV colorspace of an image projected by the projector PJ, the lightness and colorcoordinates corresponding to an input value Rin of the R component, aninput value Gin of the G component, and an input value Bin of the Bcomponent, by modifying the conversion equation shown in FIG. 7 using aconversion matrix defined, for example, in ITU-R (InternationalTelecommunications Union—Radiocommunication Sector) BT. 601. Therefore,the adjustment parameters for providing the lightness and colorcoordinates may be outputted to the projector PJ.

The image adjustment apparatus 200 then sends a command containing theadjustment parameters calculated in the step S26 to the projector PJ(step S28), and the series of processes described above are terminated(End). The projector PJ, which has received the adjustment parametersfrom the image adjustment apparatus 200, adjusts the lightness andchromaticity of the entire projected image based on the adjustmentparameters.

In FIG. 12, the description has been made with reference to the casewhere a test image is captured with the optical filter FL detached andthen the test image is captured with the optical filter FL attached, butthe invention is not limited thereto. For example, a test image mayfirst be captured with the optical filter FL attached, and the testimage may then be captured with the optical filter FL detached.

As described above, according to the first embodiment, it is notnecessary to prepare an expensive multiband capturing device, but thenumber of bands can be increased at a low cost in multiband measurement.Further, since it is not necessary to provide any optical filter on thecapturing device side, the capturing device will not be displaced due toan optical filter attaching operation, and the mechanism for attachingthe capturing device can be simplified.

Moreover, when an optical filter is provided on the side of thecapturing device, the thickness of the optical filter causes slightrefraction, sometimes resulting in a discrepancy, for example, byapproximately several pixels between an image captured with the opticalfilter detached and an image captured with the optical filter attached.In contrast, according to the first embodiment, since an optical filterthat allows the number of bands to be virtually increased in multibandmeasurement is provided in the projector PJ, the slight refractionresulting from the thickness of the optical filter can be ignored byproviding a light stop in the projector PJ. Therefore, no discrepancy inimage position will occur between the state in which the optical filteris attached and the state in which the optical filter is detached, andit is not necessary to consider the refraction resulting from thethickness of the optical filter.

Second Embodiment

While the first embodiment has been described by assuming that thespectral sensitivity characteristics of the capturing device 300 areknown, the spectral sensitivity characteristics of the capturing device300 are not necessarily known in the invention.

In a second embodiment according to the invention, a spectraldistribution estimator corresponding to the spectral distributionestimator 222 shown in FIG. 4 can estimate the spectral distributionassociated with the projector PJ even when the spectral sensitivitycharacteristics of the capturing device 300 are unknown. Since thesecond embodiment only differs from the first embodiment in terms of theconfiguration and operation of the spectral distribution estimator, theconfiguration and operation of the projector adjustment system in thesecond embodiment that are the same as those in the first embodimentwill not be illustrated or described.

The estimation of the spectral distribution associated with a projectorPJ2 in the second embodiment is, for example, based on the estimationmethod described in Reference Literature 2 (Francis Schmitt, HansBrettel, Jon Yngve Hardeberg, “Multispectral Imaging Development atENST”, Display and Imaging 8, 2000, pp. 261-268). The ReferenceLiterature 2 describes a method for estimating the spectral reflectanceof an imaged object whose spectral reflectance is unknown when thespectral sensitivity characteristics of the capturing device 300 isunknown. In the method, the spectral reflectance is estimated bymeasuring a subject whose spectral reflectance is known (Munsell chroma)under illumination whose spectral distribution is known to calculate thespectral sensitivity characteristics of the capturing device. Therefore,as in the first embodiment, captured image data obtained under apredetermined condition by multiband measurement using a small number ofbands can be used to estimate the spectral distribution associated withthe projector obtained when the light from the projector is reflectedoff a screen.

As described above, in the second embodiment, the spectralcharacteristics of the projector is estimated based on captured imagedata on an image projected by the projector using the light that has notpassed through an optical filter and captured image data on an imageprojected by the projector using the light that has passed through theoptical filter, and the estimated spectral distribution is convertedinto color coordinates in a predetermined color space. Thereafter, thethus produced conversion information is used to calculate adjustmentparameters. That is, in the second embodiment, an adjustment parametercalculation step in FIG. 12 includes an estimation step of estimatingthe spectral characteristics of the projector PJ based on the firstcaptured image data acquired in the step S14 and the second capturedimage data acquired in the step S22 and a conversion step of convertingthe spectral distribution estimated in the estimation step into colorcoordinates in a predetermined color space, and adjustment parametersare calculated based on the color coordinates obtained in the conversionstep.

The second embodiment described above can also provide the sameadvantage as that provided in the first embodiment.

Third Embodiment

While the optical filter FL is detachably provided between the crossdichroic prism 160 and the projection lens 170 in the first or secondembodiment, the invention is not limited to the arrangement describedabove.

FIG. 13 shows an exemplary configuration of a projection unit 400 in athird embodiment according to the invention. In FIG. 13, the portionsthat are the same as those in FIG. 9 have the same reference characters,and no description of these portions will be made as appropriate.

The configuration of the projection unit 400 in the third embodimentdiffers from the configuration of the projection unit 100 shown in FIG.9 in terms of the position of the optical filter FL detachably disposedin the optical path. That is, the optical filter FL is detachablyprovided between the light source 110 and the color separation system.In FIG. 13, the optical filter FL is detachably provided between theintegrator lens 112 and the integrator lens 114. That is, the opticalfilter FL can be disposed in the optical path in a position downstreamof the integrator lens 112 or a position outside the optical path.

When the optical filter FL is disposed in the optical path in a positiondownstream of the integrator lens 112 (when the optical filter FL isattached), the light having exited through the integrator lens 112 isincident on the optical filter FL. The optical filter FL removes(reflects) the light containing predetermined spectral componentswhereas transmitting the light containing the remaining spectralcomponents, as described above. The light having passed through theoptical filter FL is incident on the integrator lens 114.

On the other hand, when the optical filter FL is not disposed in theoptical path in any position downstream of the integrator lens 112 (whenthe optical filter FL is detached), the light having exited through theintegrator lens 112 does not pass through the optical filter FL but isdirectly incident on the integrator lens 114.

The optical filter FL in this case is formed of two optical filterpieces FL1 and FL2 obtained by splitting the optical filter FL at thecenter, and a moving mechanism (not shown) opens and closes the opticalfilter pieces FL1 and FL2 like bi-parting doors by turning each of theoptical filter pieces FL1 and FL2 around the corresponding one of bothends of the optical filter FL.

The mechanism for moving the optical filter FL described above may be amechanism manually operated or a mechanism controlled by controlinformation from the image adjustment apparatus 200 or the projector PJ.

In the third embodiment, the optical filter FL is not necessarilydivided into two, but an undivided optical filter may be used as in thefirst or second embodiment.

The projection unit 400 in the third embodiment can be used in theprojector PJ in place of the projection unit 100 shown in FIG. 3.

The third embodiment described above can provide the same advantage asthat provided in the first or second embodiment.

Fourth Embodiment

While the optical filter FL is detachably provided between the crossdichroic prism 160 and the projection lens 170 in the first and secondembodiments or between the light source 110 and the color separationsystem in the third embodiment, the invention is not limited to thearrangements described above.

FIG. 14 shows an exemplary configuration of a projection unit 500 in afourth embodiment according to the invention. In FIG. 14, the portionsthat are the same as those in FIG. 9 have the same reference characters,and no description of these portions will be made as appropriate.

The configuration of the projection unit 500 in the fourth embodimentdiffers from the configuration of the projection unit 100 shown in FIG.9 in terms of the position of the optical filter FL detachably disposedin the optical path. In the fourth embodiment, the optical filter FL isdetachably provided in the optical path of the light having passedthrough the integrator lens 114 between the integrator lens 114 and thepolarization conversion element 116. That is, the optical filter FL canbe disposed in the optical path of the light having passed through theintegrator lens 114 or a position outside the optical path of the lighthaving passed through the integrator lens 114.

When the optical filter FL is disposed in the optical path in a positiondownstream of the integrator lens 114 (when the optical filter FL isattached), the light having exited through the integrator lens 114 isincident on the optical filter FL. The optical filter FL removes(reflects) the light containing predetermined spectral componentswhereas transmitting the light containing the remaining spectralcomponents, as described above. The light having passed through theoptical filter FL is incident on the polarization conversion element116.

On the other hand, when the optical filter FL is not disposed in theoptical path in any position downstream of the integrator lens 114 (whenthe optical filter FL is detached), the light having exited through theintegrator lens 114 does not pass through the optical filter FL but isdirectly incident on the polarization conversion element 116.

In the thus configured projection unit 500, a moving mechanism (notshown) moves the optical filter FL into the optical path of the lightflux described above or to a position outside the optical path. Forexample, the optical filter FL is disposed in an illumination opticalaxis of the light source 110 in such a way that the optical filter FL issubstantially perpendicular to the illumination optical axis, and themoving mechanism (not shown) can translate the optical filter FL out ofthe optical path. Conversely, the moving mechanism can translate theoptical filter FL located in a position outside the optical path intothe optical path in such a way that the optical filter FL issubstantially perpendicular to the illumination optical axis of thelight source 110.

The mechanism for moving the optical filter FL described above may be amechanism manually operated or a mechanism controlled by controlinformation from the image adjustment apparatus 200 or the projector PJ.

The projection unit 500 in the fourth embodiment can be used in theprojector PJ in place of the projection unit 100 shown in FIG. 3.Further, the position of the optical filter FL is not limited to theposition shown in FIG. 13 or 14. The same advantage is provided as longas the optical filter FL is disposed in any position between the lightsource 110 and the color separation system.

The fourth embodiment described above can provide the same advantage asthose provided in the first to third embodiments.

Fifth Embodiment

While the first to fourth embodiments have been described with referenceto the case where the 3-band capturing device 300 can be used tovirtually perform 6-band multiband measurement by detachably providingthe optical filter FL between the cross dichroic prism 160 and theprojection lens 170 or between the light source 110 and the colorseparation system, the invention is not limited thereto. For example,the optical filter FL may be detachably provided in any of the opticalpaths of the color separation system that forms the projection unit ofthe projector PJ.

FIG. 15 shows an exemplary configuration of a projection unit 600 in afifth embodiment according to the invention. In FIG. 15, the portionsthat are the same as those in FIG. 9 have the same reference characters,and no description of these portions will be made as appropriate.

The configuration of the projection unit 600 in the fifth embodimentdiffers from the configuration of the projection unit 100 shown in FIG.9 in terms of the position of the optical filter FL detachably disposedin the optical path. In the fifth embodiment, the optical filter FL isdetachably provided in the optical path of the light having passedthrough the dichroic mirror for the R component 120R between thedichroic mirror for the R component 120R and the dichroic mirror for theG component 120G. That is, the optical filter FL can be disposed in theoptical path of the light having passed through the dichroic mirror forthe R component 120R or a position outside the optical path of the lighthaving passed through the dichroic mirror for the R component 120R.

When the optical filter FL is disposed in the optical path of the lighthaving passed through the dichroic mirror for the R component 120R (whenthe optical filter FL is attached), the light having passed through thedichroic mirror for the R component 120R is incident on the opticalfilter FL. The optical filter FL removes (reflects) the light containingpredetermined spectral components whereas transmitting the lightcontaining the remaining spectral components, as described above. Thelight having passed through the optical filter FL is incident on thedichroic mirror for the G component 120G.

On the other hand, when the optical filter FL is disposed in a positionoutside the optical path of the light having passed through the dichroicmirror for the R component 120R (when the optical filter FL isdetached), the light having passed through the dichroic mirror for the Rcomponent 120R does not pass through the optical filter FL but isdirectly incident on the dichroic mirror for the G component 120G.

In the thus configured projection unit 600, a moving mechanism (notshown) moves the optical filter FL into the optical path of the lightflux described above or to a position outside the optical path. Forexample, the optical filter FL is disposed in the illumination opticalaxis in such a way that the optical filter FL is substantiallyperpendicular thereto, and the moving mechanism (not shown) translatesthe optical filter FL out of the optical path in such a way that one ofthe two sides of the optical filter FL that are perpendicular to a planecontaining the illumination optical axis (the plane corresponding to theplane of view in FIG. 15), the side close to the dichroic mirror for theG component 120G disposed downstream of the optical filter FL in theoptical path and far away from the dichroic mirror for the R component120R disposed upstream of the optical filter FL in the optical path, ismoved toward the upstream side of the optical path and the opposite sideis positioned on the downstream side of the light path, as indicated bythe arrow M1 in FIG. 15.

Alternatively, the moving mechanism may rotate the optical filter FL insuch a way that the vicinity of one of the two sides of the opticalfilter FL that are perpendicular to a plane containing the illuminationoptical axis (the plane corresponding to the plane of view in FIG. 15),the side close to the dichroic mirror for the G component 120G disposeddownstream of the optical filter FL in the optical path and far awayfrom the dichroic mirror for the R component 120R disposed upstream ofthe optical filter FL in the optical path, is used as an axis to rotatethe opposite side, as indicated by the arrow M2 in FIG. 15.

When the optical filter FL is moved by the former mechanism, the spacerequired to move the optical filter FL into the optical path or to aposition outside the optical path can be smaller than that required inthe case where the latter mechanism is used, whereby the size of theoptical system and hence the size of the projector can be reduced. Incontrast, when the optical filter FL is moved by the latter mechanism,the configuration of the moving mechanism can be simplified as comparedto the case where the former mechanism is used, whereby themanufacturing step can be simplified and the manufacturing cost can bereduced.

The mechanism for moving the optical filter FL described above may be amechanism manually operated or a mechanism controlled by controlinformation from the image adjustment apparatus 200 or the projector PJ.

The projection unit 600 in the fifth embodiment can be used in theprojector PJ in place of the projection unit 100 shown in FIG. 3.

According to the fifth embodiment described above, the 3-band capturingdevice 300 can be used to perform multiband measurement with the numberof bands greater than three, although measurement precision is slightlylower than that provided in the first to fourth embodiments because thenumber of bands is smaller. As a result, it is not necessary to preparean expensive multiband capturing device, but the number of bands can beincreased at a low cost in multiband measurement, as in the first tofourth embodiments. Further, since it is not necessary to provide anyoptical filter on the side of the capturing device, the capturing devicewill not be displaced due to an optical filter attaching operation, andthe mechanism for attaching the capturing device can be simplified.Moreover, no discrepancy in image position will occur between the statein which the optical filter is attached and the state in which theoptical filter is detached, and it is not necessary to consider therefraction resulting from the thickness of the optical filter.

Sixth Embodiment

While the optical filter FL is detachably provided between the dichroicmirror for the R component 120R and the dichroic mirror for the Gcomponent 120G in the fifth embodiment, the invention is not limited tothe arrangement described above.

FIG. 16 shows an exemplary configuration of a projection unit 700 in asixth embodiment according to the invention. In FIG. 16, the portionsthat are the same as those in FIG. 9 have the same reference characters,and no description of these portions will be made as appropriate.

The configuration of the projection unit 700 in the sixth embodimentdiffers from the configuration of the projection unit 100 shown in FIG.9 in terms of the position of the optical filter FL detachably disposedin the optical path. In the sixth embodiment, the optical filter FL isdetachably provided in the optical path of the light having passedthrough the dichroic mirror for the G component 120G between thedichroic mirror for the G component 120G and the relay lens 142. Thatis, the optical filter FL can be disposed in the optical path of thelight having passed through the dichroic mirror for the G component 120Gor a position outside the optical path of the light having passedthrough the dichroic mirror for the G component 120G.

When the optical filter FL is disposed in the optical path of the lighthaving passed through the dichroic mirror for the G component 120G (whenthe optical filter FL is attached), the light having passed through thedichroic mirror for the G component 120G is incident on the opticalfilter FL. The optical filter FL removes (reflects) the light containingpredetermined spectral components whereas transmitting the lightcontaining the remaining spectral components, as described above. Thelight having passed through the optical filter FL is incident on therelay lens 142.

On the other hand, when the optical filter FL is disposed in a positionoutside the optical path of the light having passed through the dichroicmirror for the G component 120G (when the optical filter FL isdetached), the light having passed through the dichroic mirror for the Gcomponent 120G does not pass through the optical filter FL but isdirectly incident on the relay lens 142.

In the thus configured projection unit 700, a moving mechanism (notshown) moves the optical filter FL into the optical path of the lightflux described above or to a position outside the optical path. Forexample, the optical filter FL is disposed in the illumination opticalaxis in such a way that the optical filter FL is substantiallyperpendicular thereto, and the moving mechanism (not shown) translatesthe optical filter FL out of the optical path in such a way that one ofthe two sides of the optical filter FL that are perpendicular to a planecontaining the illumination optical axis (the plane corresponding to theplane of view in FIG. 16), the side close to the relay lens 142 disposeddownstream of the optical filter FL in the optical path and far awayfrom the dichroic mirror for the G component 120G disposed upstream ofthe optical filter FL in the optical path, is moved toward the upstreamside of the optical path and the opposite side is positioned on thedownstream side of the optical path, as indicated by the arrow M3 inFIG. 16.

Alternatively, the moving mechanism may rotate the optical filter FL insuch a way that the vicinity of one of the two sides of the opticalfilter FL that are perpendicular to a plane containing the illuminationoptical axis (the plane corresponding to the plane of view in FIG. 16),the side close to the relay lens 142 disposed downstream of the opticalfilter FL in the optical path and far away from the dichroic mirror forthe G component 120G disposed upstream of the optical filter FL in theoptical path, is used as an axis to rotate the opposite side, asindicated by the arrow M4 in FIG. 16.

When the optical filter FL is moved by the former mechanism, the spacerequired to move the optical filter FL into the optical path or to aposition outside the optical path can be smaller than that required inthe case where the latter mechanism is used, whereby the size of theoptical system and hence the size of the projector can be reduced. Incontrast, when the optical filter FL is moved by the latter mechanism,the configuration of the moving mechanism can be simplified as comparedto the case where the former mechanism is used, whereby themanufacturing step can be simplified and the manufacturing cost can bereduced.

The mechanism for moving the optical filter FL described above may be amechanism manually operated or a mechanism controlled by controlinformation from the image adjustment apparatus 200 or the projector PJ.

The projection unit 700 in the sixth embodiment can be used in theprojector PJ in place of the projection unit 100 shown in FIG. 3.

The sixth embodiment can provide the same advantage as that provided inthe fifth embodiment.

Seventh Embodiment

The first to sixth embodiments have been described with reference to thecase where the optical filter FL is detachably provided in the opticalpath between the light source 110 and the projection lens 170, theinvention is not limited thereto. In a seventh embodiment according tothe invention, the optical filter FL is detachably disposed in front ofthe light-exiting surface of the projection lens of the projector PJ.

FIG. 17 is an exemplary perspective view showing an exterior key portionof the projector PJ in the seventh embodiment according to theinvention. FIG. 17 is a perspective view of the projector PJ viewed fromthe front but obliquely downward. In FIG. 17, the portions that are thesame as those in FIG. 9 have the same reference characters, and nodescription of these portions will be made as appropriate.

A housing 800 that houses the portions that form the projector PJincludes an upper case 810 that forms an upper portion of the housing800, a lower case 820 that forms a lower portion of the housing 800, anda front case 830 that forms a front portion of the housing 800. Anoperation panel 812 is provided on the top surface of the upper case810, and buttons and other components for activating, adjusting, andotherwise operating the projector PJ are arranged on the operation panel812. An opening is provided in the front case 830, and a front portionof the projection lens 170 is exposed to the outside through theopening. A focus operation using the projection lens 170 can be manuallycarried out by rotating a lever 172, which is part of the exposedportion, and the optical filter FL can be attached to the front end ofthe projection lens 170.

A cylindrical holding member 840 holds the outer circumference of theoptical filter FL, and the holding member 840 fits on a front endportion of the projection lens 170, which is the light flux-exiting sideof the projection lens 170. More specifically, a cutout 842 is formed asan engaging portion in an end portion of the holding member 840 on theside facing the projection lens 170. When the lever 172 on theprojection lens 170 is inserted into the cutout 842, the lever 172engages the cutout 842, and the axis of the holding member 840 coincideswith the optical axis of the projection lens 170.

As described above, the state in which the optical filter FL is attachedand the state in which the optical filter FL is detached can be readilyachieved in the projector in the seventh embodiment, and the projectorconfigured as shown in FIG. 17 can be used as the projector PJ shown inFIG. 3.

According to the seventh embodiment, the 3-band capturing device 300 canbe used to virtually perform 6-band multiband measurement, as in thefirst to third embodiments. The configuration of the projector PJ can besignificantly simplified in the seventh embodiment as compared to thefirst to third embodiments, whereby precise multiband measurement can beperformed at a lower cost.

While several types of projector adjustment method, projector, andprojector adjustment system have been described above with reference tothe above embodiments of the invention, the invention is not limited tothe embodiments described above, but can be implemented in a variety ofaspects to the extent that they do not depart from the spirit of theinvention. For example, the following variations are possible:

1. While the image adjustment apparatus 200 is provided external to theprojector PJ in the embodiments described above, the invention is notlimited to this arrangement. For example, the projector PJ may have thefunction of the image adjustment apparatus 200.

2. While the above embodiments have been described with reference to thecase where a projector is adjusted, the invention is not limitedthereto. For example, the invention is applicable to a variety of imageadjustment systems for adjusting an image formed by a liquid crystaldisplay apparatus, a plasma display apparatus, an organic EL displayapparatus, or other similar apparatus.

3. While the above embodiments have been described with reference to thecase where a transmissive liquid crystal panel is used as the lightmodulation device (light modulator), the invention is not limitedthereto. The light modulation device (light modulator) may be DLP(Digital Light Processing)®, LCOS (Liquid Crystal On Silicon), or othersuitable components.

4. While the above embodiments have been described with reference to thecase where the invention relates to a projector adjustment method, aprojector, a projector adjustment system, and a projector adjustmentprogram, the invention does not necessarily relate thereto. For example,the invention may relate to a program in which a process procedure forimplementing the invention is written and a recording medium on whichthe program is recorded.

The entire disclosure of Japanese Patent Application No. 2009-050329,filed Mar. 4, 2009 is expressly incorporated by reference herein.

1. A method for adjusting a projector that modulates a plurality oftypes of color light based on image information to project an image, themethod comprising: acquiring first captured image data by using acapturing device to capture a first projected image projected with anoptical filter that removes predetermined spectral components notdisposed in an optical path inside or outside the projector; acquiringsecond captured image data by using the capturing device to capture asecond projected image projected with the optical filter disposed in theoptical path; calculating an adjustment parameter for adjusting theprojector based on the first and second captured image data; andadjusting the projector based on the adjustment parameter calculated inthe adjustment parameter calculation.
 2. The method for adjusting aprojector according to claim 1, wherein the adjustment parameter iscalculated in the adjustment parameter calculation, provided that thefirst and second captured image data are acquired by using bands thenumber of which is greater than the number of bands used in thecapturing device.
 3. The method for adjusting a projector according toclaim 1, wherein the adjustment parameter calculation includesestimating the spectral distribution associated with the projector basedon the first and second captured image data and the spectral sensitivitycharacteristics of the capturing device, and converting the spectraldistribution estimated in the estimation into color coordinates in apredetermined color space, and the adjustment parameter is calculatedbased on the color coordinates obtained in the conversion.
 4. The methodfor adjusting a projector according to claim 1, wherein the adjustmentparameter calculation includes estimating the spectral distributionassociated with the projector based on the first and second capturedimage data, and converting the spectral distribution estimated in theestimation into color coordinates in a predetermined color space, andthe adjustment parameter is calculated based on the color coordinatesobtained in the conversion.
 5. The method for adjusting a projectoraccording to claim 1, wherein the image information corresponding to thefirst projected image is the same as the image information correspondingto the second projected image.
 6. The method for adjusting a projectoraccording to claim 1, wherein at least one of the luminance andchromaticity of the entire projected image is adjusted in the adjustmentof the projector based on the adjustment parameter.
 7. A projector thatmodulates a plurality of types of color light based on image informationto project an image, the projector comprising: a projection unitincluding a light source, a light modulation device that modulates theplurality of types of color light contained in the light flux emittedfrom the light source based on the image information, and a projectionlens that projects the light modulated by the light modulation device;an optical filter detachably provided in an optical path inside oroutside the projection unit, the optical filter removing predeterminedspectral components; and a capturing device that captures an imageprojected by the projection unit, wherein the capturing device acquiresfirst captured image data by capturing a first projected image projectedwith the optical filter not disposed in the optical path inside oroutside the projection unit and acquires second captured image data bycapturing a second projected image projected with the optical filterdisposed in the optical path.
 8. The projector according to claim 7,wherein at least one of the luminance and chromaticity of the entireprojected image is adjusted based on the first and second captured imagedata.
 9. A projector adjustment system for adjusting a projector thatmodulates a plurality of types of color light based on image informationto project an image, the system comprising: the projector according toclaim 7; and an image adjustment apparatus that adjusts an imageprojected by the projector, wherein the image adjustment apparatusincludes a captured image data analyzer that analyzes the first andsecond captured image data, and an adjustment parameter calculator thatcalculates an adjustment parameter for adjusting the projector based onthe analysis result obtained from the captured image data analyzer, andthe image projected by the projector is adjusted based on the adjustmentparameter.
 10. The projector adjustment system according to claim 9,wherein the adjustment parameter calculator calculates the adjustmentparameter, provided that the first and second captured image data areacquired by using bands the number of which is greater than the numberof bands used in the capturing device.
 11. The projector adjustmentsystem according to claim 9, wherein the captured image data analyzerestimates the spectral distribution associated with the projector basedon the first and second captured image data and the spectral sensitivitycharacteristics of the capturing device, and converts the estimatedspectral distribution into color coordinates in a predetermined colorspace, and the adjustment parameter calculator calculates the adjustmentparameter based on the color coordinates converted by the captured imagedata analyzer.
 12. The projector adjustment system according to claim 9,wherein the captured image data analyzer estimates the spectraldistribution associated with the projector based on the first and secondcaptured image data, and converts the estimated spectral distributioninto color coordinates in a predetermined color space, and theadjustment parameter calculator calculates the adjustment parameterbased on the color coordinates converted by the captured image dataanalyzer.
 13. The projector adjustment system according to claim 9,wherein the image information corresponding to the image projected byusing the light that has passed through the optical filter is the sameas the image information corresponding to the image projected by usingthe light that has not passed through the optical filter.
 14. Theprojector adjustment system according to claim 9, the projector adjustsat least one of the luminance and chromaticity of the entire projectedimage based on the adjustment parameter.